#include <bits/stdc++.h>

#define FOR(a,b,c) for(int a=(b),_for=(c);a<_for;++a)
#define ll long long
#define vi vector < int >
#define pii pair < int, int >
#define x first
#define y second
#define mp make_pair
#define pb push_back
#define PCNT(a) __builtin_popcount(a)

using namespace std;

int p[50];
char c[50];
int n;

int main(){
	FOR(i,0,26) scanf ("%d",p+i);
	scanf ("%s",c);
	n=strlen(c);
	int x=0;
	FOR(i,0,n) x=max(x,p[c[i]-'a']);
	printf ("%d\n",x*n);
	return 0;
}